As shown in Japanese Patent Application laid open to public No. 63-94140, the conventional optical disks have a structure in which the side face of the recording layer is not covered with such a film as a ceramic protection film, a metallic reflective film, or the like. As shown in U.S. Pat. No. 4,731,620, the adhesion layer using UV-curing resin can be formed only in the region in which no recording layer is formed. Furthermore, the adhesion layer using thermo-setting resin is directly connected to the substrate in the outer circumference region of the substrate, as shown in U.S. Pat. No. 4,731,620.
On the other hand, the conventional processes for fabricating optical disks use only either UV-curing or thermo-setting resin.
However, the structure of the above optical disks has problems in that
(1) the adhesion strength is low in the inner and outer circumference parts of the substrate, and that PA1 (2) the side face of the recording layer tends to degrade. PA1 (1) strain tends to occur in the substrates because they are laid in the thermo-setting step, and that PA1 (2) the adhesive tends to overflow the side face of the substrate in the hardening step and the like of the adhesive. PA1 (1) an optical disk having a first substrate, a second substrate and an adhesive layer pasting the above first and second substrates together, characterized in that the optical disk has, on each of the substrates, a first protecting layer formed thereon, a recording layer formed on the said first protecting layer, a second protecting layer formed on the said recording layer, a reflective layer formed on the said second protecting layer within the region outer than the central hole bored on the above substrates and inner than the outer diameter of the above substrates, and a ceramic layer formed on the said reflective layer within the region surrounded by a diameter smaller than the inner diameters of the above reflective layer and the above recording layer and a diameter larger than the outer diameters of the above reflective layer and the above recording layer;
Furthermore, the processes for fabricating the above optical disks have problems in that
Accordingly, the present invention has been achieved in order to solve the above described problems. An object of the present invention is to increase the weather resistance of the recording layer, a second object is to make it possible to set the substrates upright in the thermo-setting step, and a third object is to prevent the adhesive from overflowing in the thermo-setting process and the like.